The analysis of thermoelectric powder compaction mechanisms within field-activated sintering of skutterudites and Heusler alloys

Abstract

The analysis of the shrinkage rate of powders, based on the power-law creep model of a porous body, was carried out in this paper to calculate the compaction parameters of CoSb3-based skutterudites and Fe2VAl-based Heusler alloys within field-activated sintering. It was indicated that this method, which had already been used for metal and ceramic powders, is applicable for thermoelectric powders. The values of strain rate sensitivity were obtained, and the corresponding powder compaction mechanisms have been defined. The main creep mechanism for skutterudites was found to be a dislocation climb, that later was replaced by grain boundary sliding, and the last sintering stage was associated with diffusional creep. The main creep mechanism for Heusler alloys was grain boundary sliding, later replaced by diffusional creep. Keywords: field-assisted sintering, numerical simulation, powders compaction, skutterudites, Heusler alloys, thermoelectrics.